It is well known for the hearing impaired to utilize keyboards through an attached modem for communication over a sound linked telephone handset. In such an application, the keyboard communicates directly to a portable acoustical modem having a handset cradle. The acoustical modem then has input to the telephone handset. Communication with another keyboard can follow.
Call boxes are known. Generally, such call boxes are cellular telephones powered by solar charged batteries and rest in a dormant state at a road side. Upon being approached for use, such telephones power up and place a cellular telephone call to a pre-programmed number. When the cellular telephone call is placed, such telephones are interactive with a dispatch center for verifying location, status, periodic reporting, and most importantly initiating emergency telephone calls by the public.
To date, such call boxes have not been provided with Telecommunications Devices for the Deaf (TDD) or Text Telephone (TT) capability. In what follows, there is disclosed an interactive protocol which enables an interface to be transparently utilized by existing call boxes and to interactively cooperate with an answering dispatch center.